Actuation Linkage for Centrifugal Compressor Vanes
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Solution Overview
Problem
Existing linkage assemblies for actuating guide vanes in centrifugal compressors, such as those in HVAC systems, face challenges with high loading conditions due to denser refrigerants, leading to wear and performance issues in fork and rod designs, and complexity and cost in rack and pinion configurations.
Innovation Solution
A robust linkage assembly with a lever arm and transition linkage configuration that translates forces effectively, providing ease of adjustability, high reliability, and hermetic integrity, utilizing a linear actuator to maximize drive axis leverage and featuring a spherical rod end bearing for efficient motion conversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If fork and rod configurations are used as actuation components, then the structure is relatively light weight, but the components are susceptible to wear issues and performance issues under high loading conditions
Solution Approach 1:
The patent changes the structural parameters of the actuation components from fork and rod configurations to a linkage assembly with lever arms and transition linkages. This parameter change allows the system to handle higher loading conditions while maintaining acceptable weight, resolving the contradiction between light weight and reliability under high loading.
Solution Approach 2:
The patent employs a spherical rod end bearing in the linkage assembly to convert rotational motion to linear motion. This curved/spherical interface provides better load distribution and reduces wear compared to straight rod configurations, improving reliability under high loading while maintaining the lightweight advantage.
2Reliability
If rack and pinion gear configurations are used as actuation components, then the structure is more robust, but the design is relatively expensive and complex requiring great care during assembly
Solution Approach 1:
The patent extracts the gear mechanism from the actuation system and replaces it with a linkage assembly using lever arms and transition linkages. This removes the complex rack and pinion gear configuration while maintaining robustness, eliminating the need for precise gear alignment during assembly.
Solution Approach 2:
The patent introduces a transition linkage as an intermediary component that converts rotational motion from the shaft to linear motion for actuating the guide vanes. This intermediary mechanism provides a simpler alternative to direct gear engagement, reducing assembly complexity while maintaining structural robustness.
3Device complexity
If fork and rod designs are used, then the structure is simpler, but the components create greater moment on the driver ring causing additional side forces and deflection
Solution Approach 1:
The patent designs the linkage assembly with lever arms positioned to maximize leverage on the drive axis before forces are transmitted to the driver ring. This preliminary mechanical advantage reduces the moment and side forces applied to the driver ring, addressing the force issue while maintaining structural simplicity.
Solution Approach 2:
The spherical rod end bearing in the transition linkage provides a curved interface that better distributes forces and reduces concentrated side forces on the driver ring. This curved geometry maintains simplicity while reducing the harmful moments and deflections caused by straight rod configurations.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The linkage assembly effectively handles high loading conditions, reduces wear, and is cost-effective, maintaining hermetic integrity while providing reliable actuation of guide vanes, even under increased pressure from denser refrigerants.
Implementation Method 1
featuring a spherical rod end bearing for efficient motion conversion
Implementation Method 2
The embodiments herein can maximize leverage for example of the drive axis for actuation
Data Source
AI summary
An actuation linkage assembly may include a first lever arm connected to one end of a shaft, a second lever arm connected at one end to another end of the shaft, a transition linkage connected to the other end of the second lever arm, and a bracket connected to the transition linkage. The transition linkage is configured to connect the bracket on a driver ring and to the shaft to transfer rotational motion about the axis of the shaft, from a linear motion received by an actuator, to a linear motion through the bracket causing rotational motion of the driver ring. The actuation linkage assembly is configured with high mechanical advantage. The actuation linkage assembly can be part of a movable inter-stage vane guide assembly in a compressor such as for example a centrifugal compressor, which may be part of a chiller such as in a HVAC system.